TPS65266: please help check wehther the VIN can be powered after EN, thanks

user5324035

Part Number: TPS65266

In our designing, we connect VIN1, VIN3,VINQ,EN1,EN2,EN3 together, but connect VIN2 to other circuit, which to ensure the LX2 will be powered after Lx1 and LX3.

It means, the EN2 will be powered before VIN2.

based on the testing, we found this circuit is working, and when VIN2 being powered, LX2 will be enabled after about 15ms, it is much longer than that between VIN1/VIN3 and LX1/Lx3( which is about 2ms).

Please help confirm whether this designing is normal and whether there is risk or not.

thanks

over 5 years ago

0 Sam(MPAA) Zhang over 5 years ago

TI__Mastermind 19080 points

Hi,

It should be good to enable the part before VIN2 is applied, but I'm curious about the 15ms time interval you mentioned. Can you post the waveform of VIN2, SS2, EN2, and Vout2? I'd like to check if the part is working well.
Thanks!

Regards,
Hao

0 user5324035 over 5 years ago in reply to Sam(MPAA) Zhang

Intellectual 290 points

please refer below picture for the waveform, thanks

0 user5324035 over 5 years ago in reply to user5324035

Intellectual 290 points

0 user5324035 over 5 years ago in reply to user5324035

Intellectual 290 points

the delay between EN2 and VIN2 caused by other delay circuit.
what we concern is the delay from VIN2 to SS2, it is strange.
and below picture is the circuit relate to 65266, thanks

0 user5324035 over 5 years ago in reply to user5324035

Intellectual 290 points

0 user5324035 over 5 years ago in reply to Sam(MPAA) Zhang

Intellectual 290 points

please help check the waveform and schematic, thanks.

0 Sam(MPAA) Zhang over 5 years ago in reply to user5324035

TI__Mastermind 19080 points

Hi,

When VIN1/3 are applied, and EN1-3 is high, the internal logic power supply V7V is present. All of the blocks start to operate. For CH2, as VIN2 is not applied, this channel is in a condition of UVP and entered the hiccup mode. Time interval between VIN2 ramp up and Vout2 ramp up depends on the hiccup beat.
So, the the design is not correct. Please split the EN2 and enble CH2 after VIN2 applied.
Any further qeustion, please let me know. Thanks!

Regards,
Hao

0 user5324035 over 5 years ago in reply to Sam(MPAA) Zhang

Intellectual 290 points

So do you mean, if we just adopt VIN2, the VIN2 can be powered after EN2, If we adopt VIN1~3, the VIN2 can not be powered after VINi,3, VEN 1,2,3, like our schematic, am I right?

So the schematic should be changed as below : powered VIN1~3, VEN1,VEN3 at firstly, and control the delay by powered the VEN2, am I right?

0 Sam(MPAA) Zhang over 5 years ago in reply to user5324035

TI__Mastermind 19080 points

Hi,

Yes, you are right. Please use EN2 to control the Vout2.

Regards,
Hao

0 user5324035 over 5 years ago in reply to Sam(MPAA) Zhang

Intellectual 290 points

Thanks a lot...

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TPS65266: please help check wehther the VIN can be powered after EN, thanks